定义
字典树，又称为单词查找树，Tire数，是一种树形结构，它是一种哈希树的变种。用于保存大量的字符串。它的优点是：利用字符串的公共前缀来节约存储空间。
字典树结构对应的Java源码
public class Trie {
char val;
boolean isEnd = false;
Trie[] subChildren = new Trie[26];
public Trie(char val) {
this.val = val;
}
}
字典树增删改查对应的Java源码
本次示例仅展示了insert,find方法
public class TrieDemo {
Trie root = new Trie(' ');
public void insert(String word) {
Trie node = root;
for (int i = 0; i < word.length(); i++) {
char c = word.charAt(i);
int idx = c - 65;
if (node.subChildren[idx] == null) {
Trie sub = new Trie(c);
node.subChildren[idx] = sub;
}
node = node.subChildren[idx];
}
node.isEnd = true;
}
public boolean exist(String word) {
Trie node = root;
for (int i = 0; i < word.length(); i++) {
char c = word.charAt(i);
int idx = c - 65;
if (node.subChildren[idx] == null) {
return false;
}
node=node.subChildren[idx];
}
return node.isEnd;
}
public static void main(String[] args) {
TrieDemo demo = new TrieDemo();
demo.insert("HELLO");
System.out.println(demo.root);
boolean f = demo.exist("HELLO");
System.out.println(f);
}
}
字典树增删改查线程安全版本对应的Java源码
public class TrieSynchronizedDemo {
Trie root = new Trie(' ');
public void insert(String word) {
Trie node = root;
for (int i = 0; i < word.length(); i++) {
char c = word.charAt(i);
int idx = c - 65;
if (node.subChildren[idx] == null) {
synchronized (node) {
if (node.subChildren[idx] == null) {
Trie sub = new Trie(c);
node.subChildren[idx] = sub;
}
}
}
node = node.subChildren[idx];
}
node.isEnd = true;
}
public boolean exist(String word) {
Trie node = root;
for (int i = 0; i < word.length(); i++) {
char c = word.charAt(i);
int idx = c - 65;
if (node.subChildren[idx] == null) {
return false;
}
node = node.subChildren[idx];
}
return node.isEnd;
}
public static void main(String[] args) {
TrieSynchronizedDemo demo = new TrieSynchronizedDemo();
demo.insert("HELLO");
System.out.println(demo.root);
boolean f = demo.exist("HELLO");
System.out.println(f);
}
}
